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Abstract:

Example embodiments relate to an organic semiconductor polymer, in which
fused thiophenes having liquid crystal properties and aromatic compounds
having N-type semiconductor properties are alternately included in the
main chain of the polymer, an organic active layer, an organic thin film
transistor (OTFT), and an electronic device including the same, and
methods of preparing the organic semiconductor polymer, and fabricating
the organic active layer, the OTFT and the electronic device using the
same. This organic semiconductor polymer has improved organic solvent
solubility, processability, and thin film properties, and may impart
increased charge mobility and decreased off-state leakage current when
applied to the channel layer of the organic thin film transistor.

Claims:

1. An organic semiconductor polymer, which is represented by Formula 1
below:wherein Ar is a C.sub.2.about.30 heteroaromatic ring containing one
or more electron-accepting imine nitrogen atoms, one or more hydrogen
atoms of the heteroaromatic ring being substituted with Rs, in which the
Rs, which are same as or different from each other, are each a hydroxyl
group, a C.sub.1.about.20 linear, branched or cyclic alkyl group, a
C.sub.1.about.20 alkoxyalkyl group, or a C.sub.1.about.16 linear,
branched or cyclic alkoxy group,T is a group containing about
2.about.about 6 fused thiophene rings,D is a C.sub.4.about.14 hetero
arylene group containing a hetero atom, other than a nitrogen atom, in an
aromatic ring, or a C.sub.6.about.30 arylene group,a is an integer from
about 1 to about 4,x is an integer from about 2 to about 6,y is an
integer from about 0 to about 4, andn is an integer from about 4 to about
200.

2. The organic semiconductor polymer as set forth in claim 1, wherein the
Ar of Formula 1 is one or more selected from a group represented by
Formula 2 below:wherein Y is a C.sub.1.about.20 linear, branched or
cyclic alkyl group, an aryl group, or a C.sub.1.about.16 linear, branched
or cyclic alkoxy group.

3. The organic semiconductor polymer as set forth in claim 1, wherein the
T of Formula 1 is one or more selected from a group represented by
Formula 3 below:wherein R1 to R6, which are same as or
different from each other, are each hydrogen, a hydroxyl group, a
C.sub.1.about.20 linear, branched or cyclic alkyl group, a
C.sub.1.about.20 alkoxyalkyl group, or a C.sub.1.about.16 linear,
branched or cyclic alkoxy group.

4. The organic semiconductor polymer as set forth in claim 1, wherein the
hetero arylene group of the D of Formula 1 is a 5-membered hetero arylene
group substituted with one or more elements selected from among S, N--H,
O, and Se, andthe D of Formula 1 is substituted with a hydroxyl group, a
C.sub.1.about.20 linear, branched or cyclic alkyl group, a
C.sub.1.about.20 alkoxyalkyl group, a C.sub.˜16 linear, branched or
cyclic alkoxy group, or one or more elements selected from among F, Br,
Cl and I.

5. The organic semiconductor polymer as set forth in claim 1, wherein the
D of Formula 1 is selected from a group represented by Formula 4
below:wherein X is S, N--H, O or Se.

6. The organic semiconductor polymer as set forth in claim 1, wherein the
organic semiconductor polymer represented by Formula 1 is selected from a
group represented by Formula 11 below:wherein n is an integer from about
4 to about 200.

7. The organic semiconductor polymer of claim 1, wherein the organic
semiconductor polymer has a number average molecular weight ranging from
about 5,000 to about 100,000.

9. The organic active layer as set forth in claim 8, wherein the organic
active layer is formed using a coating process selected from a group
consisting of screen printing, printing, spin coating, dipping, and ink
jetting.

10. An organic thin film transistor, comprising a substrate, a gate
electrode, a gate insulating layer, an organic active layer, and
source/drain electrodes, wherein the organic active layer is the organic
active layer according to claim 8.

11. The organic thin film transistor as set forth in claim 10, wherein the
gate insulating layer is formed of a ferroelectric insulator selected
from a group consisting of Ba.sub.0.33Sr.sub.0.66TiO3 (BST),
Al2O3, Ta2O5, La2O5, Y2O3, and
TiO2, an inorganic insulator selected from a group consisting of
PbZr.sub.0.33Ti.sub.0.66O3 (PZT), Bi4Ti3O12,
BaMgF4, SrBi2(TaNb)2O9, Ba(ZrTi)O3 (BZT),
BaTiO3, SrTiO3, Bi4Ti.sub.30.sub.12, SiO2, SiNx,
and AlON, or an organic insulator selected from a group consisting of
polyimide, benzocyclobutane (BCB), parylene, polyacrylate,
polyvinylalcohol, and polyvinylphenol.

12. The organic thin film transistor as set forth in claim 10, wherein the
gate electrode and the source/drain electrodes are formed of a material
selected from a group consisting of gold (Au), silver (Ag), aluminum
(Al), nickel (Ni), and indium tin oxide (ITO)

13. The organic thin film transistor as set forth in claim 10, wherein the
substrate is formed of a material selected from a group consisting of
glass, polyethylene naphthalate (PEN), polyethylene terephthalate (PET),
polycarbonate, polyvinylalcohol, polyacrylate, polyimide, polynorbornene,
and polyethersulfone (PES).

14. An electronic device comprising the organic thin film transistor of
claim 10.

15. The electronic device as set forth in claim 14, wherein the electronic
device is selected from the group consisting of a photovoltaic device, an
organic electroluminescent device, and a sensor.

16. A method of preparing an organic semiconductor polymer, comprising
copolymerizing a monomer represented by Formula 5 below with a monomer
represented by Formula 6 below:X1--Ar--Ar--X2 Formula
5wherein Ar is a C.sub.2.about.30 heteroaromatic ring containing one or
more electron-accepting imine nitrogen atoms, one or more hydrogen atoms
of the heteroaromatic ring being substituted with Rs, in which the Rs,
which are same as or different from each other, are each a hydroxyl
group, a C.sub.1.about.20 linear, branched or cyclic alkyl group, a
C.sub.1.about.20 alkoxyalkyl group, or a C.sub.1.about.16 linear,
branched or cyclic alkoxy group, andX1 and X2 are each a
halogen atom, including Br, Cl or I, a trialkyltin group, or a borane
group; andX3-(T)a-X4 Formula 6wherein T is a group
containing 2.about.6 fused thiophene rings and is selected from a group
consisting of Formula 3 below,X3 and X4 are each a halogen
atom, including Br, Cl or I, a trialkyltin group, or a borane group, anda
is an integer from about 1 to about 4:wherein R1 to R6 are
defined as in R of Formula 5.

17. The method as set forth in claim 16, wherein the method is conducted
in a presence of a catalyst represented by Formula 7 or 8 below:PdL4
or PdL2Cl2 Formula 7wherein L is a ligand selected from a
group consisting of triphenylphosphine (PPh3), triphenylarsine
(AsPh3), and triphenylphosphite (P(OPh)3); andNiL'2 or
NiL'Cl2 Formula 8wherein L' is a ligand selected from a group
consisting of 1,5-cyclooctadiene, 1,3-diphenylphosphinopropane,
1,2-bis(diphenylphosphino)ethane, and 1,4-diphenylphosphinobutane.

18. A method of forming an organic active layer comprising preparing the
organic semiconductor polymer according to claim 16.

19. A method of fabricating an organic thin film transistor,
comprising:forming a gate electrode, a gate insulating layer, an organic
active layer, and source/drain electrodes on a substrate, wherein the
organic active layer is formed according to claim 18.

20. The method as set forth in claim 19, wherein the organic thin film
transistor has a top contact structure or a bottom contact structure.

21. A method of fabricating an electronic device comprising fabricating
the organic thin film transistor according to claim 19.

22. A method of preparing an organic semiconductor polymer, comprising
copolymerizing a monomer represented by Formula 9 below with a monomer
represented by Formula 10 below:X1 Ar T Ar X2 Formula
9wherein Ar is a C.sub.2.about.30 heteroaromatic ring containing one or
more electron-accepting imine nitrogen atoms, one or more hydrogen atoms
of the heteroaromatic ring being substituted with Rs, in which the Rs,
which are same as or different from each other, are each a hydroxyl
group, a C.sub.1.about.20 linear, branched or cyclic alkyl group, a
C.sub.1.about.20 alkoxyalkyl group, or a C.sub.1.about.16 linear,
branched or cyclic alkoxy group, andX1 and X2 are each a
halogen atom, including Br, Cl or I, a trialkyltin group, or a borane
group,T is a group containing about 2.about.about 6 fused thiophene rings
and is selected from a group represented by Formula 3 below,a is an
integer from about 1 to about 4, andx is an integer from about 2 to about
6:wherein R1 to R6 are defined as in R of Formula 9; andX3
D yX4 Formula 10wherein D is a C.sub.4.about.14 hetero
arylene group containing a hetero atom, other than a nitrogen atom, in an
aromatic ring, or a C.sub.6.about.30 arylene group,X3 and X4
are each a halogen atom, including Br, Cl or I, a trialkyltin group, or a
borane group, andy is an integer from about 1 to about 4.

23. A method of forming an organic active layer comprising preparing the
organic semiconductor polymer according to claim 22.

24. A method of fabricating an organic thin film transistor,
comprising:forming a gate electrode, a gate insulating layer, an organic
active layer, and source/drain electrodes on a substrate, wherein the
organic active layer is formed according to claim 23.

25. A method of fabricating an electronic device comprising fabricating
the organic thin film transistor according to claim 24.

Description:

PRIORITY STATEMENT

[0001]This non-provisional application claims priority under U.S.C.
§119 to Korean Patent Application No. 10-2007-0047717, filed on May
16, 2007, with the Korean Intellectual Property Office (KIPO), the entire
contents of which are herein incorporated by reference.

BACKGROUND

[0002]1. Field

[0003]Example embodiments relate to an organic semiconductor polymer
having liquid crystal properties, an organic active layer, an organic
thin film transistor (OTFT), and an electronic device including the same,
and methods of preparing the organic semiconductor polymer, and
fabricating an organic active layer, an OTFT and an electronic device
using the same. Other example embodiments relate to an organic
semiconductor polymer having liquid crystal properties, in which fused
thiophenes having liquid crystal properties and aromatic compounds having
N-type semiconductor properties are alternately included in the main
chain of the polymer, thus simultaneously imparting both increased charge
mobility and decreased off-state leakage current, an organic active
layer, an organic thin film transistor (OTFT), and an electronic device
including the same, and methods of preparing the organic semiconductor
polymer, and fabricating an organic active layer, an OTFT and an
electronic device using the same.

[0004]2. Description of the Related Art

[0005]In general, an OTFT, including a substrate, a gate electrode, an
insulating layer, source/drain electrodes, and a channel layer, is
classified into a bottom contact (BC) type, in which the channel layer is
formed on the source/drain electrodes, and a top contact (TC) type, in
which a metal electrode is formed on the channel layer through mask
deposition.

[0006]The channel layer of the OTFT may be formed of an inorganic
semiconductor material, for example, silicon (Si). However, with the
fabrication of relatively large, inexpensive, and flexible displays, the
use of an organic semiconductor material, instead of an expensive
inorganic material requiring a high-temperature vacuum process, may be
required.

[0007]Research has been directed to organic semiconductor material for the
channel layer of the OTFT, and the transistor properties thereof have
been reported. Examples of low-molecular-weight or oligomeric organic
semiconductor materials may include merocyanine, phthalocyanine,
perylene, pentacene, C60, and thiophene oligomer. According to the
related art, the use of pentacene monocrystals may result in increased
charge mobilities of 3.2˜5.0 cm2/Vs and above. In addition,
relatively increased charge mobility of 0.01˜0.1 cm2/Vs and
on/off current ratio using an oligothiophene derivative have been
reported. However, these techniques may be dependent on a vacuum process
for the formation of a thin film.

[0008]Further, there may be OTFTs using an organic semiconductor polymer
material, which is exemplified by a thiophene polymer. Although these
OTFTs may have properties inferior to OTFTs using low-molecular-weight
organic semiconductor material, processability may be improved because a
relatively large area may be realized at decreased expense through a
solution process, for example, a printing process. In this regard, the
related art has reported the experimental fabrication of a polymer-based
OTFT using a polythiophene material, called F8T2, leading to charge
mobility of 0.01˜0.02 cmM2/Vs. As mentioned above, the organic
semiconductor polymer material has TFT properties, including charge
mobility, inferior to those of low-molecular-weight organic semiconductor
material, including pentacene, but the organic semiconductor polymer
material may eliminate the need for an increased operating frequency and
may enable the inexpensive fabrication of TFTs.

[0009]With the goal of commercializing OTFTs, an increased on/off current
ratio may be an important characteristic to be realized in addition to
charge mobility. To this end, off-state leakage current may be minimized
or reduced. The related art discloses an OTFT including an active layer
composed of n-type inorganic semiconductor material and p-type organic
semiconductor material to thus slightly improve the characteristics of
the OTFT, which is nevertheless difficult to use in mass production
because the fabrication process is similar to a conventional Si-based TFT
process requiring deposition. In addition, the related art discloses an
OTFT having charge mobility of 0.01˜0.04 cm2/Vs using
regioregular poly(3-hexylthiophene) (P3HT). In the case of using
poly(3-hexylthiophene) (P3HT) as a typical regioregular material, the
charge mobility may be about 0.01 cm2/Vs, but the on/off current
ratio may be relatively low, e.g., as low as about 400 or lower, due to
the increased off-state leakage current (about 10-9 A and above),
and consequently the above material is limited in application to
electronic devices.

[0010]Moreover, organic semiconductor materials having liquid crystal
properties capable of realizing increased charge mobility have been
studied. For example, the related art discloses a semiconductor material
containing (2,3-b)-thienothiophene to thus improve charge mobility,
processability, and oxidation stability. Although such an organic
semiconductor polymer material may function to increase charge mobility,
the pi-pi conjugation length of the organic semiconductor polymer may not
be effectively controlled, undesirably making it difficult to satisfy
both increased charge mobility and decreased off-state leakage current.

SUMMARY

[0011]Accordingly, example embodiments provide an organic semiconductor
polymer, in which fused thiophenes having liquid crystal properties and
aromatic compounds having N-type semiconductor properties are alternately
included in the main chain of the polymer, thus simultaneously imparting
both increased charge mobility and decreased off-state leakage current,
an organic active layer, an organic thin film transistor (OTFT) having
increased charge mobility and decreased off-state leakage current, and an
electronic device including the same, and methods of preparing the
organic semiconductor polymer, and fabricating an organic active layer,
an OTFT and an electronic device using the same.

wherein Ar is a C2˜30 heteroaromatic ring containing one or
more electron-accepting imine nitrogen atoms, one or more hydrogen atoms
of the heteroaromatic ring may be substituted with Rs, in which the Rs,
which are the same as or different from each other, are each a hydroxyl
group, a C1˜20 linear, branched or cyclic alkyl group, a
C1˜20 alkoxyalkyl group, or a C1˜16 linear,
branched or cyclic alkoxy group, T is a group containing 2˜6 fused
thiophene rings, D is a C4-14 hetero arylene group containing a
hetero atom, other than a nitrogen atom, in an aromatic ring, or a
C6˜30 arylene group, a is an integer from about 1 to about 4,
x is an integer from about 2 to about 6, y is an integer from about 0 to
about 4, and n is an integer from about 4 to about 200.

[0013]Example embodiments also provide an organic active layer, an organic
thin film transistor (OTFT) having increased charge mobility and
decreased off-state leakage current, and an electronic device including
the same, and methods of preparing the organic semiconductor polymer, and
fabricating an organic active layer, an OTFT and an electronic device
using the same.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]Example embodiments will be more clearly understood from the
following detailed description taken in conjunction with the accompanying
drawings. FIGS. 1˜3 represent non-limiting example embodiments
described herein.

[0016]FIG. 2 is a graph illustrating the results of DSC (Differential
Scanning Calorimetry) of the organic semiconductor polymer obtained in
the preparative example of example embodiments; and

[0017]FIG. 3 is a graph illustrating the current transfer properties of
the device fabricated in the example of example embodiments.

[0018]It should be noted that these figures are intended to illustrate the
general characteristics of methods, structures and/or materials utilized
in certain example embodiments and to supplement the written description
provided below. These drawings are not, however, to scale, and may not
precisely reflect the precise structural or performance characteristics
of any given embodiment, and should not be interpreted as defining or
limiting the range of values or properties encompassed by the example
embodiments. In particular, the relative thicknesses and positioning of
molecules, layers, regions and/or structural elements may be reduced or
exaggerated for clarity. The use of similar or identical reference
numbers in the various drawings is intended to indicate the presence of a
similar or identical element or feature.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0019]Hereinafter, a detailed description will be given of example
embodiments with reference to the appended drawings. Example embodiments
may, however, be embodied in many different forms and should not be
construed as being limited to the embodiments set force herein. Rather,
these embodiments are provided so that this disclosure will be thorough
and complete, and will fully convey the scope of example embodiments to
those skilled in the art.

[0020]In the drawings, the thickness of layers and regions are exaggerated
for clarity. It will also be understood that when an element such as a
layer, region or substrate is referred to as being "on" or "onto" another
element, it may lie directly on the other element or intervening elements
or layers may also be present. Like reference numerals refer to like
elements throughout the specification.

[0021]It will be understood that, although the terms first, second, third
etc. may be used herein to describe various elements, components,
regions, layers and/or sections, these elements, components, regions,
layers and/or sections should not be limited by these terms. These terms
are only used to distinguish one element, component, region, layer or
section from another region, layer or section. Thus, a first element,
component, region, layer or section discussed below could be termed a
second element, component, region, layer or section without departing
from the teachings of example embodiments.

[0022]Spatially relative terms, such as "beneath," "below," "lower,"
"above," "upper" and the like, may be used herein for ease of description
to describe one element or feature's relationship to another element(s)
or feature(s) as illustrated in the figures. It will be understood that
the spatially relative terms are intended to encompass different
orientations of the device in use or operation in addition to the
orientation depicted in the figures. For example, if the device in the
figures is turned over, elements described as "below" or "beneath" other
elements or features would then be oriented "above" the other elements or
features. Thus, the exemplary term "below" can encompass both an
orientation of above and below. The device may be otherwise oriented
(rotated 90 degrees or at other orientations) and the spatially relative
descriptors used herein interpreted accordingly.

[0023]The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of example
embodiments. As used herein, the singular forms "a," "an" and "the" are
intended to include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises" and/or "comprising," when used in this specification, specify
the presence of stated features, integers, steps, operations, elements,
and/or components, but do not preclude the presence or addition of one or
more other features, integers, steps, operations, elements, components,
and/or groups thereof.

[0024]Example embodiments are described herein with reference to
cross-sectional illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures) of example
embodiments. As such, variations from the shapes of the illustrations as
a result, for example, of manufacturing techniques and/or tolerances, are
to be expected. Thus, example embodiments should not be construed as
limited to the particular shapes of regions illustrated herein but are to
include deviations in shapes that result, for example, from
manufacturing. For example, an implanted region illustrated as a
rectangle will, typically, have rounded or curved features and/or a
gradient of implant concentration at its edges rather than a binary
change from implanted to non-implanted region. Likewise, a buried region
formed by implantation may result in some implantation in the region
between the buried region and the surface through which the implantation
takes place. Thus, the regions illustrated in the figures are schematic
in nature and their shapes are not intended to illustrate the actual
shape of a region of a device and are not intended to limit the scope of
example embodiments.

[0025]Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which example
embodiments belong. It will be further understood that terms, such as
those defined in commonly used dictionaries, should be interpreted as
having a meaning that is consistent with their meaning in the context of
the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.

wherein Ar is a C2˜30 heteroaromatic ring containing one or
more electron-accepting imine nitrogen atoms, one or more hydrogen atoms
of the heteroaromatic ring may be substituted with Rs, in which the Rs,
which are the same as or different from each other, are each a hydroxyl
group, a C1˜20 linear, branched or cyclic alkyl group, a
C1˜20 alkoxyalkyl group, or a C1˜16 linear,
branched or cyclic alkoxy group, T is a group containing about 2˜
about 6 fused thiophene rings, D is a C4˜14 hetero arylene
group containing a hetero atom, other than a nitrogen atom, in an
aromatic ring, or a C6˜30 arylene group, a is an integer from
about 1 to about 4, x is an integer from about 2 to about 6, y is an
integer from about 0 to about 4, and n is an integer from about 4 to
about 200.

[0027]The organic semiconductor polymer of example embodiments may have a
structure including heteroaromatic rings having N-type semiconductor
properties and fused thiophene rings having liquid crystal properties as
a P-type semiconductor, in which the P-type semiconductors and the N-type
semiconductors are alternately disposed in the main chain thereof. In
addition, the structure of the polymer may further include an arylene
group having P-type semiconductor properties to thus diversify the type
of P-type semiconductor used in example embodiments.

[0028]The organic semiconductor polymer represented by Formula 1 may
contain fused thiophene rings, thus exhibiting liquid crystal properties.
As a result, the organic semiconductor polymer may be uniformly oriented
and ordered and therefore allows the close packing of molecular
pi-electron systems, which maximizes or increases the intermolecular
charge transfer that occurs through a hopping mechanism between adjacent
molecules, leading to increased charge mobility.

[0029]The organic semiconductor polymer may be structured in a manner such
that the fused thiophene rings having P-type semiconductor properties and
the heteroaromatic rings having N-type semiconductor properties are
alternately disposed, thus minimizing or reducing off-state leakage
current. For example, because the heteroaromatic rings, having N-type
semiconductor properties, are disposed between the fused thiophene rings,
having liquid crystal properties and thus functioning as a P-type
semiconductor material, the pi-pi conjugation length in the molecule may
be effectively controlled, leading to decreased off-state leakage
current.

[0030]The organic semiconductor polymer may further include a compound
having P-type semiconductor properties between the heteroaromatic rings
having N-type semiconductor properties, thereby minimizing or reducing
off-state leakage current.

[0031]In addition, the organic semiconductor polymer may include a side
chain containing an alkyl group introduced in the main chain thereof, in
order to increase solubility and processability.

[0032]In Formula 1, Ar, which is a C2˜30 heteroaromatic ring
containing one or more electron-accepting imine nitrogen atoms, may be
selected from a group represented by Formula 2 below, but example
embodiments are not limited thereto:

wherein Y is a C1˜20 linear, branched or cyclic alkyl group, an
aryl group, or a C1˜16 linear, branched or cyclic alkoxy
group.

[0036]Said T of Formula 1 may be selected from a group represented by
Formula 3 below, but example embodiments are not limited thereto:

wherein R1 to R6, which are the same as or different from each
other, are each hydrogen, a hydroxyl group, a C1˜20 linear,
branched or cyclic alkyl group, a C1˜20 alkoxyalkyl group, or
a C1˜16 linear, branched or cyclic alkoxy group.

[0037]Among compounds represented by Formula 3, said T may be
thieno[3,2-b]thiophene, which enables the effective control of the pi
conjugation length in the polymer semiconductor molecule to thus assure
decreased leakage current, and which also has improved planar properties
to thus promote pi-pi interactions, leading to increased charge mobility.

[0038]Further, the hetero arylene group of D of Formula 1 may be a
5-membered hetero arylene group substituted with one or more elements
selected from among S, N--H, O, and Se, and D of Formula 1 may be
substituted with a hydroxyl group, a C1˜20 linear, branched or
cyclic alkyl group, a C1˜20 alkoxyalkyl group, a
C1˜16 linear, branched or cyclic alkoxy group, or one or more
elements selected from among F, Br, Cl and I.

[0039]The heteroarylene group and the arylene group may be one or more
selected from a group represented by Formula 4 below, but example
embodiments are not limited thereto:

wherein X is S, N--H, O or Se.

[0040]A method of synthesizing the organic semiconductor polymer, in which
y of Formula 1 is about 0, may include polymerizing a monomer represented
by Formula 5 below with a monomer represented by Formula 6 below in the
presence of a catalyst represented by Formula 7 or 8 below, but example
embodiments are not limited thereto:

X1--Ar--Ar--X2 Formula 5

wherein Ar is defined as in Formula 1, and X1 and X2 are each a
halogen atom, including Br, Cl or I, a trialkyltin group, or a borane
group;

X3-(T)a-X4 Formula 6

wherein T is a group containing about 2˜about 6 fused thiophene
rings, and may be selected from the group represented by Formula 3,
X3 and X4 are each a halogen atom, including Br, Cl or I, a
trialkyltin group, or a borane group, and a is an integer from about 1 to
about 4;

PdL4 or PdL2Cl2 Formula 7

wherein L is a ligand selected from the group consisting of
triphenylphosphine (PPh3), triphenylarsine (ASPh3), and
triphenylphosphite (P(OPh)3); and

NiL'2 or NiL'Cl2 Formula 8

wherein L' is a ligand selected from the group consisting of
1,5-cyclooctadiene, 1,3-diphenylphosphinopropane,
1,2-bis(diphenylphosphino)ethane, and 1,4-diphenylphosphinobutane.

[0041]Specific examples of the nickel (0) catalyst may include
bis(1,5-cyclooctadiene)nickel (0) [Ni(COD)2], and examples of the nickel
(II) catalyst include 1,3-diphenylphosphinopropane nickel (II)
chloride[Ni(dppp)Cl2], and 1,2-bis(diphenylphosphino)ethane nickel
(II) chloride [Ni(dppe)Cl2].

[0043]In the method of example embodiments, the polymerization may be
conducted using a solvent, for example, toluene, dimethylformaldehyde
(DMF), tetrahydrofuran (THF), or N-methylpyrrolidinone (NMP), at about
60° C.˜about 120° C. for about 5˜about 72 hours
in a nitrogen atmosphere.

[0044]In addition, a method of preparing the organic semiconductor
polymer, in which y of Formula 1 is about 1˜about 4, may include
polymerizing a monomer represented by Formula 9 below and a monomer
represented by Formula 10 below, in the presence of the catalyst of
Formula 7 or 8, but example embodiments are not limited thereto:

wherein Ar is a C2˜30 heteroaromatic ring containing one or
more electron-accepting imine nitrogen atoms, one or more hydrogen atoms
of the heteroaromatic ring may be substituted with Rs, in which the Rs,
which are the same as or different from each other, are each a hydroxyl
group, a C1˜20 linear, branched or cyclic alkyl group, a
C1˜20 alkoxyalkyl group, or a C1˜16 linear,
branched or cyclic alkoxy group, X1 and X2 are each a halogen
atom, including Br, Cl or I, a trialkyltin group, or a borane group, T is
a group containing about 2˜ about 6 fused thiophene rings and may
be selected from a group represented by Formula 3 below, a is an integer
from about 1 to about 4, and x is an integer from about 2 to about 6:

wherein R1 to R6 are defined as in R of Formula 9; and

X3 D yx4 Formula 10

wherein D is a C4˜14 hetero arylene group containing a hetero
atom, other than a nitrogen atom, in an aromatic ring, or a
C6˜30 arylene group, X3 and X4 are each a halogen
atom, including Br, Cl or I, a trialkyltin group, or a borane group, and
y is an integer from about 1 to about 4.

[0045]Typical examples of the organic semiconductor polymer represented by
Formula 1 may include, but are not limited to, compounds selected from a
group represented by Formula 11 below:

wherein n is an integer from about 4 to about 200.

[0046]The organic semiconductor polymer of example embodiments may have a
number average molecular weight ranging from about 5,000 to about
100,000, for example, from about 10,000 to about 100,000.

[0047]The organic semiconductor polymer of example embodiments may
function as a material for a charge generation layer and a charge
transport layer of an electronic device, including a photovoltaic device,
an organic electroluminescent device, and a sensor, but example
embodiments are not limited thereto. The structure of the electronic
device is known in the art, and thus a description thereof is omitted.

[0048]An OTFT may be fabricated using the organic semiconductor polymer of
example embodiments as an organic semiconductor material for the active
layer thereof. The organic active layer may be formed through screen
printing, printing, spin coating, dipping, or ink jetting, but example
embodiments are not limited thereto.

[0049]FIG. 1A is a schematic sectional view illustrating a bottom contact
type OTFT, and FIG. 1B is a schematic sectional view illustrating a top
contact type OTFT. The OTFT may be formed into a typically known
structure, including a substrate 1, a gate electrode 2, a gate insulating
layer 3, source/drain electrodes 4,5, and an organic active layer 6, as
illustrated in FIG. 1A, or alternatively including a substrate 1, a gate
electrode 2, a gate insulating layer 3, an organic active layer 6, and
source/drain electrodes 4, 5, as illustrated in FIG. 1B, but example
embodiments may not be limited thereto.

[0050]The gate insulating layer of the OTFT may be formed of a typically
used insulating material having a high dielectric constant, and specific
examples of the insulating material may include, but are not limited to,
a ferroelectric insulator including Ba0.33Sr0.66TiO3 (BST:
Barium Strontium Titanate), Al2O3, Ta2O5,
La2O5, Y2O3 and TiO2, an inorganic insulator
(see: U.S. Pat. No. 5,946,551) including PbZr0.33Ti0.66O3
(PZT), Bi4Ti3O12, BaMgF4,
SrBi2(TaNb)2O9, Ba(ZrTi)O3 (BZT), BaTiO3,
SrTiO3, Bi4Ti3012, SiO2, SiNx and AlON, or
an organic insulator (see: U.S. Pat. No. 6,232,157) including polyimide,
benzocyclobutane (BCB), parylene, polyacrylate, polyvinylalcohol and
polyvinylphenol.

[0051]The gate electrode and the source/drain electrodes of the OTFT may
be formed of typically used metal, and specific examples of the metal may
include, but are not limited to, gold (Au), silver (Ag), aluminum (Al),
nickel (Ni), and indium tin oxide (ITO).

[0052]Examples of material for the substrate of the OTFT may include, but
are not limited to, glass, polyethylene naphthalate (PEN), polyethylene
terephthalate (PET), polycarbonate, polyvinylalcohol, polyacrylate,
polyimide, polynorbornene, and polyethersulfone (PES).

[0053]A better understanding of example embodiments may be obtained in
light of the following examples, which are set forth to illustrate, but
are not to be construed as limiting example embodiments.

PREPARATIVE EXAMPLE

Synthesis of Compound-1

[0055]Compound-1 was synthesized from monomers (1) and (2) through a
Yamamoto polymerization method.
2,5-dibromo-3,6-didodecyl-thieno[3,2-b]thiophene (about 0.6 g, about
0.946 mmol), as a monomer (1), and
5,5'-bis-trimethylstannyl-[2,2]bithiazolyl (about 0.47 g, about 0.946
mmol) were placed in a reactor in a nitrogen atmosphere, completely
dissolved in anhydrous DMF under decreased heat conditions, added with a
palladium (0) compound Pd(PPh3)4 (about 10 mol % based on the
total amount of the monomers) as a polymerization catalyst, and then
allowed to react at about 85° C. for about 5 hours. After the
completion of the reaction, the reaction solution was cooled to about
room temperature and filtered, thus obtaining a polymer solid. The
polymer solid was washed two times with an aqueous hydrochloric acid
solution/chloroform, two times with an aqueous ammonia
solution/chloroform, and then two times with water/chloroform,
reprecipitated in methanol, recovered, and dried, yielding a red
compound-1 (yield: about 0.3 g, number average m.w.=about 10,000).

Preparation of Monomer (1)

[0056]1. Synthesis of Tridecanoyl Chloride (B)

[0057]In a 1 L three-neck round-bottom flask, a compound A (tridecanoic
acid) (about 35 g, about 163.3 mmol) was placed, and dissolved in
SOCl2 (about 300 ml). This solution was refluxed for about 2 hours,
and was then cooled, after which SOCl2 was concentrated under
reduced pressure, thus obtaining about 39 g (y=about 99%) of tridecanoyl
chloride B. 1H NMR of the obtained compound B was as follows.

[0058]1H NMR (300 MHz, CDCl3)

[0059] 0.88 (t, 3H), 1.30 (m, 18H), 1.68 (m, 2H), 2.88 (t, 2H)

2. Synthesis of 1-(3,4-Dibromothiophen-2-Nyl)-Trideca-1-None (C)

[0060]In a 1 L round-bottom flask, the compound B (about 39 g, about 167
mmol) and 3,4-dibromothiophene (about 39.5 g, about 163.3 mmol) were
placed, and dissolved in methylene chloride (about 500 ml). This solution
was slowly added with AlCl3 (about 21.8 g, about 163.3 mmol) over
about 30 minutes, and was then stirred for about 3 hours. After the
completion of the reaction, the stirred solution was added with distilled
water (about 200 ml), and was then extracted with methylene chloride
(about 300 ml). Subsequently, the organic layer was washed with an about
1 N sodium hydroxide solution, washed with brine (about 300 ml), dried
over magnesium sulfate, filtered, concentrated, and then subjected to
column chromatography (H:E=50:1), thus obtaining about 55.6 g (y=about
77%) of 1-(3,4-dibromothiophen-2-nyl)-trideca-1-none C. 1H NMR of
the obtained compound C was as follows.

[0066]In a 1 L two-neck round-bottom flask, the compound D (about 59.5 g,
about 129.5 mmol) was placed, and dissolved in ethanol (about 600 ml).
The solution was added with sodium hydroxide (about 10.4 g, about 259.0
mmol), refluxed for about 1 hour to remove ethanol, dissolved in
distilled water (about 500 ml), and then acidified with about 35% HCl.
The solid was filtered, stirred in hexane, and further filtered, thus
obtaining about 48.3 g (y=about 86%) of
6-bromo-3-dodecyl-thieno[3,2-b]thiophene-2-carboxylic acid E. 1H NMR
of the obtained compound E was as follows.

[0069]In a 1 L three-neck round-bottom flask, the compound E (about 43.5
g, about 101 mmol) was placed, and dissolved in quinoline (about 250 ml),
after which the solution was heated to about 200° C. and stirred
for about 30 minutes. The stirred solution was cooled, and was then
extracted with ethyl acetate (about 2 L), after which the extracted
organic layer was washed two times with about 5 N hydrochloric acid
solution (about 500 ml), washed with about 2N hydrochloric acid (about
500 ml), and washed with brine (about 500 ml). The organic layer was
dried over magnesium sulfate, filtered, concentrated under reduced
pressure, and then subjected to column chromatography using hexane, thus
obtaining about 31.6 g (y=about 80%) of
6-bromo-3-dodecyl-thieno[3,2-b]thiophene F. 1H NMR of the obtained
compound F was as follows.

[0072]In a 500 ml steel bomb, the compound F (about 27.6 g, about 71.3
mmol) was placed, and dissolved in triethylamine (about 200 ml). The
solution was added with 1-dodecyne (about 23 ml, about 106.9 mmol),
copper iodide (about 1.4 g, about 7.13 mmol), and palladium
triphenylphosphine (about 1.65 g, about 1.4 mmol), and was then heated at
about 150° C. for about 24 hours. The solution was further added
with hexane (about 500 ml), and the salt was filtered through celite. The
extracted organic layer was washed three times with 2 N hydrochloric acid
(about 100 ml), washed with brine (about 100 ml), dried over magnesium
sulfate, filtered, concentrated under reduced pressure, and then
subjected to column chromatography (hexane), thus obtaining about 10.55 g
(y=about 31%) of 3-dodecyl-6-dodecy-1-nyl-thieno[3,2-b]thiophene G.

7. Synthesis of 3,6-Didodecyl-Thieno[3,2-b]Thiophene (H)

[0073]In a 500 ml par bottle, the compound G (about 10.55 g, about 22.3
mmol) was placed, and dissolved in ethyl acetate (about 200 ml). The
solution was added with about 10% palladium/carbon (about 2.1 g) and
hydrogen (gas, about 30 psi), and was then stirred for about 24 hours.
Thereafter, the stirred solution was filtered through celite,
concentrated, and recrystallized using ethanol, thus obtaining about 7.76
g (y=about 72%) of 3,6-didodecyl-thieno[3,2-b]thiophene H. 1H NMR of
the obtained compound H was as follows.

[0076]In a 500 ml round-bottom flask, the compound H (about 7.76 g, about
16.3 mmol) was placed, and dissolved in methylene chloride (about 300
ml). The solution was added with N-bromosuccinimide (about 6.4 g, about
35.8 mmol), allowed to react for about 24 hours, and added with water
(about 100 ml), after which the organic layer was washed with brine
(about 100 ml). The organic layer was dried over magnesium sulfate,
filtered, and concentrated, after which the solid was washed with
methanol, thereby obtaining about 10 g (y=about 96%) of
2,5-dibromo-3,6-didodecyl-thieno[3,2-b]thiophene I. 1H NMR of the
obtained compound I was as follows.

[0077]1H NMR (300 MHz, CDCl3)

[0078] 0.87 (t, 6H), 1.25 (m, 36H), 1.65 (m, 4H), 2.66 (t, 4H)

Synthesis of Monomer (2)

[0079]Synthesis of Chloroacetaldehyde (b)

[0080]1) A 1 L round-bottom flask was dried and was then filled with
nitrogen. [0081]2) About 400 ml of Methylene Chloride and
dimethylsulfoxide (about 30.6 ml, about 431 mmol) were sequentially
placed in the reactor, and were then cooled to about -78° C.
[0082]3) In a 500 ml round-bottom flask, about 100 ml of methylene
chloride, the compound A (about 21.6 g, about 490 mmol), and about 2 ml
of MeOH were placed and mixed together. [0083]4) Oxalyl chloride (about
37 ml, about 291 mmol) was added in droplets to the solution of 2) for
about 30 minutes, and the resultant solution was stirred for about 1
hour. [0084]5) The solution of 3) was added in droplets to the solution
of 4) for about 1 hour. [0085]6) The mixed solution was stirred for about
1 hour while the temperature was maintained at about -78° C.
[0086]7) Triethylamine (about 120 ml, about 860 mmol) was added in
droplets to the solution of 6) for about 2 hours, and the obtained
solution was stirred for about 15 hours in a nitrogen atmosphere.
[0087]8) The reaction solution was slowly added with about 400 ml of an
about 2 N hydrochloric acid solution, and was then stirred at about room
temperature for about 1 hour. [0088]9) The reaction solution was
transferred into a separate funnel, after which the organic layer was
separated, and was then washed with an about 2 N aqueous hydrochloric
acid solution. [0089]10) The organic layer was washed with brine and
further separated, after which the obtained organic layer was dried over
magnesium sulfate and was then concentrated under reduced pressure, thus
obtaining about 24 g of chloroacetaldehyde b as a yellowish brown solid.

2. Synthesis of [2,2']-Bisthiazolyl (c)

[0090]The compound b (about 19.5 g, about 24.8 mmol) was dissolved in
about 300 ml of ethanol in a nitrogen atmosphere, and was then added with
1,1,3,3-tetramethyl urea (about 2.8 g, about 24.8 mmol). The solution was
added with dithiooximide (about 2.4 g, about 12.4 mmol) and was then
refluxed for about 48 hours. This solution was added with the compound
(a) (about 4 g, about 90.8 mmol) and triethyl orthoacetate (about 4 g,
about 24.8 mmol), and was then refluxed for about 24 hours. The reaction
solution was cooled to about room temperature, concentrated under reduced
pressure, and crystallized from acetonitrile, thus obtaining about 5 g of
[2,2']-bisthiazolyl c in a solid phase.

3. Synthesis of 5,5'-Dibromo-[2,2']Bithiazolyl (d)

[0091]In a reactor, the compound c (about 5 g, about 29.6 mmol) was
placed, dissolved in a mixture of about 150 ml of chloroform and about
150 ml of acetic acid, added with N-bromosuccinimide (about 10.5 g, about
59.3 mmol), and then stirred for about 10 hours in a state in which the
reactor was enshrouded with silver foil. After the completion of the
reaction, the resultant reaction solution was filtered, and washed
several times with acetonitrile. The solution was heated and crystallized
using acetonitrile, thus obtaining about 4 g of
5,5'-dibromo-[2,2']bithiazolyl d in a solid phase.

4. Synthesis of 5,5'-Bistrimethylstannyl-[2,2']Bithiazolyl (e)

[0092]In a 1 L flask, the compound d (about 4 g, about 12 mmol) was
placed, dissolved in THF (about 200 ml), slowly added with n-butyllithium
(about 10.6 ml, about 26.4 mmol) at about -30° C., and then
stirred for about 1 hour. The stirred solution was slowly added with
methyltin chloride (about 25.5 ml, about 25.5 mmol) at about -78°
C., stirred for about 2 hours, added with distilled water (about 200 ml),
and extracted with ether (about 600 ml). The extracted organic layer was
washed with brine (about 300 ml), dried over magnesium sulfate, filtered,
and concentrated under reduced pressure. The resultant compound was
dissolved in ether and crystallized at about -78° C., after which
the solid product was dissolved in acetone and crystallized at about
-10° C.˜about -20° C., thus obtaining about 3.5 g
(y=about 39%) of 5,5'-bistrimethylstannyl-[2,2']bithiazolyl e in a solid
phase. 1H NMR of the obtained compound e was as follows.

[0093]1H NMR (300 MHz, CDCl3)

[0094] 7.794 (s, 2H), 0.44 (s, 18)

EXAMPLE

Fabrication of OTFT using Compound-1

[0095]On a washed glass substrate, chromium for a gate electrode was
deposited to a thickness of about 1000 Å through sputtering, after
which SiO2 for a gate insulating film was deposited to a thickness
of about 1000 Å through CVD. Subsequently, ITO for source/drain
electrodes was deposited thereon to a thickness of about 1200 Å
through sputtering. Before the organic semiconductor material was
deposited, the substrate was washed with isopropyl alcohol for about 10
minutes and was then dried. This sample was immersed in an
octadecyltrichlorosilane solution, which had been diluted to a
concentration of about 10 mM using chloroform, for about 30 seconds,
washed with acetone, and dried, after which the compound-1 synthesized in
the preparative example was dissolved to a concentration of about 1 wt %
in chloroform, applied to a thickness of about 1000 Å at about 1000
rpm, and baked at about 100° C for about 1 hour in an argon
atmosphere, thus fabricating the OTFT of FIG. 1A.

[0096]FIG. 2 is a graph illustrating the results of DSC (Differential
Scanning Calorimetry) of the organic semiconductor polymer obtained in
the preparative example of example embodiments, and FIG. 3 is a graph
illustrating the current transfer properties of the device fabricated in
the example of example embodiments.

[0097]As illustrated in FIG. 2, the polymer may exhibit liquid crystal
properties because it had two phase transition temperatures, about
93° C. and about 226° C., when heated, and two phase
transfer temperatures, about 80° C. and about 191.8° C.,
when cooled.

[0098]The current transfer properties of the device fabricated in the
example were measured using a semiconductor characterization system
(4200-SCS), available from KEITHLEY, and graphed in FIG. 3. The
electrical properties thereof are given in Table 1 below.

[0099]The charge mobility was calculated from the following current
equation for the saturation region. For example, the current equation for
the saturation region was converted into a graph relating
(ISD)1/2 and VG, and the charge mobility was calculated
from the slope of the converted graph:

wherein ISD is the source-drain current, μ or μFET is the
charge mobility, Co is the oxide film capacitance, W is the channel
width, L is the channel length, VG is the gate voltage, and VT
is the threshold voltage.

[0100]The off-state leakage current (Ioff), which is the current
flowing in the off-state, was taken from the minimum current in the
off-state of the on/off current ratio.

[0101]The on/off current ratio (Ion/Ioff) was taken from the
ratio of maximum current in the on-state to minimum current in the
off-state.

[0102]As is apparent from Table 1, the OTFT of the example using the
organic semiconductor polymer may have decreased off-state leakage
current and increased on/off current ratio and charge mobility.

[0103]As described hereinbefore, example embodiments provide an organic
semiconductor polymer, a method of preparing the same, and an OTFT using
the same. According to example embodiments, the organic semiconductor
polymer may include fused thiophenes having liquid crystal properties and
N-type aromatic compounds alternately disposed in the main chain thereof,
thus exhibiting improved organic solvent solubility, processability, and
thin film properties. Further, when the organic semiconductor polymer is
applied to the channel layer of the OTFT, increased charge mobility and
decreased off-state leakage current may be realized.

[0104]Although example embodiments have been disclosed for illustrative
purposes, those skilled in the art will appreciate that various
modifications, additions and substitutions are possible, without
departing from the scope and spirit of example embodiments as disclosed
in the accompanying claims.